Process for preparing a mask for use in manufacturing a semiconductor device

Abstract

A process is disclosed for preparing a mask, such as a photo-mask, used in a selective etching process in the manufacture of a semiconductor device or a protective mask for use in a process for selectively providing a porous layer of silicon or for anodic oxidation of a metal layer, in which ions accelerated at a predetermined voltage are implanted into a photo-resist film to a predetermined dose level.

What is claimed is: 
     
       1. A process for preparing a photo- mask comprising the steps of: forming a substantially transparent organic film on a transparent substrate to a thickness of 300A to 10 μm and in a predetermined pattern, said organic film being comprised of at least one material selected from the group consisting of a photo-resist, polymethyl acrylate, rubber, novolak, polyethylene, polyimide, and epoxy, and implanting in said organic film ions accelerated at an acceleration voltage of at least 50 KeV, to a dose level of at least 10 14  /cm 2  to such an extent that said organic film has an optical density that is sufficient to shield visible light and/or ultraviolet rays, thereby providing a photo-mask which selectively shields visible light and/or ultraviolet rays in said predetermined pattern.   
     
     
       2. A process for preparing a photo-mask for use in photo-etching, comprising the steps of; preparing a transparent substrate through which a visible light and/or ultraviolet rays can be transmitted, depositing a substantially transparent photo-resist film on one plane of said substrate to a thickness of 300 A to 10 μm, selectively removing said photo-resist film to leave a predetermined pattern, and implanting in said remaining photo-resist film ions accelerated at an acceleration voltage of at least 50 KeV, to a dose level of at least 10 14  /cm 2  to such an extent that said photo-resist film has an optical density that is sufficient to shield visible light and/or ultraviolet rays, thereby providing a photo-mask which selectively shields visible light and/or ultraviolet rays in said predetermined pattern.   
     
     
       3. A process for preparing a photo-mask comprising the steps of: forming a first light-shielding pattern on one surface of a transparent substrate, depositing a substantially transparent photo-resist film of a thickness of 300A to 10 μm over the entire surface of said first light-shielding pattern and that portion of said one surface of said transparent substrate on which said first light-shielding pattern is not present, selectively removing said photo-resist film lying on said first light-shielding pattern, implanting in the remaining photo-resist film ions accelerated at an acceleration voltage at least 50 KeV to a dose level of at least 10 14  /cm 2  to convert said remaining photo-resist film to a second light-shielding pattern which is negative with respect to said first light-shielding pattern, and thereafter removing said first light-shielding pattern, whereby a photo-mask having the second light-shielding pattern on the transparent substrate is obtained. 
     
     
       4. A process for repairing a photo-mask for use in photo-etching, comprising the steps of: selectively forming a substantially transparent photo-resist film of a thickness of 300A to 10μm on a predetermined portion of said photo-mask having a pattern of a light-shielding material on a transparent substrate, and implanting in said photo-resist film ions accelerated at an acceleration voltage of at least 50KeV to a dose level of at least 10 14  /cm 2  to such an extent that said photo-resist film has an optical density that is sufficient to shield visible light and/or ultraviolet rays.   
     
     
       5. A photo-mask comprising a substrate of a transparent material and a predetermined pattern of an opaque photo-resist film formed on the surface of said substrate, said photo-resist film having been made opaque by having been implanted with ions accelerated at a voltage of at least 50KeV to a dose level of at least 10 14  /cm 2  to such an extent so that said photo-resist film shields visible light and/or ultraviolet rays. 
     
     
       6. A process for preparing a photo-mask for use in photo-etching comprising the steps of preparing a transparent substrate thorugh which a visible light and/or ultraviolet rays can be transmitted, depositing a substantially transparent organic film on an entire surface of said transparent substrate, said organic film being comprised of at least one material selected from the group consisting of a photo-resist, polymethl acrylate, rubber, novolak, polyethyene, polystyrene, polyimide, and epoxy; implanting in said organic film ions accelerated at an acceleration voltage of at least 50KeV, to a dose level of at least 10 14  /cm 2  to such an extent that said organic film has an optical density sufficient to shield visible light and/or ultraviolet rays, and selectively removing said ion-implanted organic film to leave a predetermined pattern, thereby providing a photomask which selectively shields visible light and/or ultraviolet rays in said predetermined pattern. 
     
     
       7. A process according to claim 6 wherein said step of selectively removing said ion-implanted organic film includes selectively etching said ion-implanted organic film by plasma etching or sputtering etching. 
     
     
       8. A process for preparing a photo-mask for use in photo-etching comprising the steps of preparing a transparent substrate through which a visible light and/or ultraviolet rays can be transmitted, depositing a substantially transparent photo-resist film on an entire surface of said transparent substrate, implanting in said photo-resist film ions accelerated at an acceleration voltage of at least 50KeV, to a dose level of at least 10 14  /cm 2  to such an extent that said photo-resist film has an optical density sufficient to shield visible light and/or ultraviolet rays, and selectively removing said ion-implanted photo-resist film to leave a predetermined pattern, thereby providing a photo-mask which selectively shields visible light and/or ultraviolet rays in said predetermined pattern. 
     
     
       9. A process according to claim 8, wherein said step of selectively removing said ion-implanted photo-resist film includes selectively etching said ion-implanted photo-resist film by plasma etching or sputtering etching.